Such engineered wood boards are widely used in many different fields. A particularly significant field of use is use as a floor panel. With this use in particular the engineered wood boards are exposed to immense loading in particular as a result of being walked on. To ensure that they withstand this loading, the decorative layer has to be covered with a protective layer. This generally consists of a synthetic resin, for example melamine resin, to which various additives have been added. The various layers applied to the engineered wood board result in tensile stresses, which may lead to cupping of the engineered wood board. Therefore, both the top and bottom of the engineered wood board may be coated to allow these forces to occur evenly on both sides and thus to avoid cupping.
Application of the synthetic resin layer to the engineered wood board may proceed in a very wide range of ways. It is known, for example, to apply the synthetic resin as granules or powder to the side of the engineered wood board to be coated and to sprinkle in any additives provided. During final pressing, the powder applied melts under the action of pressure and heat and forms a homogeneous layer. In this method bilateral coating of the engineered wood board is of course impossible, since the sprinkled-on powder merely lies on the surface of the engineered wood board and is only bonded therewith during pressing.
It is known from EP 1 454 763 A2 to apply a protective layer of melamine resin to the decor on the top of an engineered wood board. At the same time, a protective layer of melamine resin is likewise to be applied to the bottom of the engineered wood board. The applied resin layers are then intended to melt during pressing and so enclose the decor.
EP 2 098 304 A2 describes the use of liquid resin, which is applied to both the top and bottom of the engineered wood board.